It has been found that interference or noise signals in power supplies for the switching or control circuits can lead to the program counter and storage register of a microprocessor or microcomputer being changed in such a way that the program present in the constant value storage no longer can be processed properly and only arbitrary operations can be carried out. This condition can only be remedied by a reset function, that is, by resetting of the microcomputer or microprocessor to the initial condition with the subsequent restart of the program.
It is conceivable in the case of microprocessors to check the data circuits for the occurrence of erroneous operations and to take certain measures during the existence of such operations which will result in the restarting of the program.
However, this method requires extensive decoding switching circuitry to recognize faulty operations, and further it cannot be used for microcomputers, since with these the data circuits are not readily accessible externally.